Key pointsr Considerable controversy exists regarding the role of irisin, a putative exercise-induced myokine, in human metabolism.r We therefore studied irisin and its precursor Fndc5 in obesity, type 2 diabetes and exercise. r Complex clinical studies combined with cell culture work revealed that Fndc5/irisin was decreased in type 2 diabetes in vivo, but not in muscle cells in vitro, indicating that diabetes-related factor(s) regulate Fndc5/irisin in vivo.r Several attributes of type 2 diabetes, such as hyperglycaemia, triglyceridaemia, visceral adiposity and extramyocellular lipid deposition were negatively associated with adipose tissue Fndc5 mRNA and circulating irisin. Moreover, mimicking diabetic status in vitro by treating muscle cells with palmitate and glucose lowered Fndc5 mRNA.r Neither exercise training nor an acute exercise bout modulated circulating irisin or muscle Fndc5 expression. However, the associations between intensity of habitual physical activity, muscle volume, strength, contractility and circulating irisin provide a link between irisin and positive outcomes of increased physical activity.Abstract Irisin was identified as a myokine secreted by contracting skeletal muscle, possibly mediating some exercise health benefits via 'browning' of white adipose tissue. However, a controversy exists concerning irisin origin, regulation and function in humans. Thus, we have explored Fndc5 gene and irisin protein in two clinical studies: (i) a cross-sectional study (effects of type 2 diabetes (T2D) in drug-naive men) and (ii) an intervention study (exercise effects in sedentary, overweight/obese individuals). Glucose tolerance and insulin sensitivity were assessed. Maximal aerobic capacity and muscle strength were measured before and after training. Body composition (magnetic resonance imaging), muscle and liver fat content ( 1 H-magnetic resonance spectroscopy (MRS)) and in vivo muscle metabolism ( 32 P-MRS) were determined. Skeletal muscle and subcutaneous abdominal adipose tissue samples were taken in the fasted state and during euglycaemic hyperinsulinaemia (adipose tissue) and before/after exercise training (muscle). We found that muscle Fndc5 mRNA was increased in prediabetes but not T2D. tissue and irisin in plasma were reduced in T2D by 40% and 50%, respectively.

This study evaluates the effect of 3 months resistance and aerobic training on muscle strength and power in 17 male overweight and obese men. Subjects underwent either a resistance or aerobic training for a period of 3 months (three sessions per week). Peak isometric force, rate of force development, peak power and height of countermovement and squat jumps, reactive strength index, and mean power in the concentric phase of bench presses were all assessed prior to and after completing the training program. Results identified a significant increase of mean power during both countermovement bench presses at 30 kg (18.6%, p = .021), 40 kg (14.6%, p = .033), and 50 kg (13.1%, p = .042) and concentric-only bench presses at 30 kg (19.6%, p = .017) and 40 kg (13.9%, p = .037) after the resistance training. There was also a significant increase in the height of the jump (12.8%, p = .013), peak power (10.1%, p = .026), and peak velocity (9.7%, p = .037) during the countermovement jump and height of the jump (11.8%, p = .019), peak power (9.6%, p = .032), and peak velocity (9.5%, p = .040) during the squat jump. There were no significant changes in the reactive strength index, peak force, and the rate of force development after the resistance training. The aerobic group failed to show any significant improvements in these parameters. It may be concluded that 3 months of resistance training without caloric restriction enhances upper and lower body muscle power in overweight and obese men.

Purpose. The study compares the sway variables after continuous CMJs eliciting different level of proprioceptive stimulation determined by per centage of max height of the jump. Basic procedures. A group of 11 aerobic dancers performed in random order repeated jumps with maximal effort until the jump height dropped to 75%, 50%, and 25% of previously established max jump achieved in nonfatigued conditions. The height of CMJs was calculated from flight times registered by FiTRO Jumper. Thirty seconds prior to and two minutes after exercises the COP velocity was registered at 100 Hz by means of posturography system FiTRO Sway Check based on dynamometric platform. Main findings. Results showed that max height of the jump (MJ) decreased from 27.7 ± 2.8 cm to 20.1 ± 2.6 cm when subjects matched 75% of 1MJ, to 13.8 ± 1.6 cm at 50% of 1MJ, and to 6.9 ± 0.8 cm at 25% of 1MJ. The COP velocity was significantly ( p ≤ 0.01) higher after jumps dropped to 75% of 1MJ as compared to baseline (from 9.2 ± 1.6 mm/s to 14.5 ± 2.4 mm/s). Its further significant ( p ≤ 0.05) increase was observed after jumps dropped to 50% of 1MJ (to 19.6 ± 2.6 mm/s). However, there was only slight increase in COP velocity after jumps dropped to 25% of 1MJ (to 21.4 ± 3.2 mm/s). Conclusions. Taking into account a gradual increase in sway velocity after jumps matched 75% and 50% of 1MJ and its no further increase after jumps matched 25% of 1MJ, it may be assumed that postexercise balance impairment is not linearly related to the level of proprioceptive stimulation.

Three months of resistance training in overweight and obese subjects improves reactive balance control in response to unexpected perturbations under unstable conditions, both with and without visual cues. Due to the fact that this unstable load release balance test was found to be sensitive in revealing post-training changes, it would be suitable for implementing in the functional diagnostic for this group, in addition to complementing existing testing methods.

The purpose of this study was to investigate the effect of one-year specific aerobic gymnastics training on selected anthropometric and motor parameters in 6-11-year-old girls. 23 girls (average age in the beginning of the study was 8.04 ± 1.22 years) were involved in the study representing 2 different aerobic gymnastics sports clubs in Slovakia. The selected group completed their regular trainings and competitions for a period of one year. Measurements were taken in January 2019 and January 2020, in the middle of the preparatory period. Normality of distribution of the traits was examined using the Shapiro-Wilk test. Data were analyzed using Wilcoxon signed-rank test. Considering anthropometric parameters, there were significant changes (p≤0.01) in body height, body weight and BMI. Considering motor parameters, the mean values of straddle support hold and back extension endurance test increased significantly to the level of p≤0.05. The mean values of 4x10m shuttle run, standing long jump, modified push-ups, sit-ups in 60s increased significantly to the level of p≤0.01. No significant changes were observed in bent arm hang test or hanging knee tucks. On the other hand, the values of 1 leg stand with eyes closed and 2-min endurance shuttle run decreased insignificantly.